Fit a bi-fold door — HomeGraft

Fit a bi-fold door into an existing opening, with the right fixings for whatever is behind the reveals and head.

BF-01Unpack the kit and check the openingLay out all parts and check them against the instructions - track, panels, pivots, guides and fixings packs. If you're removing an old hinged door, take it off its hinges and unscrew the old frame furniture. Check the door isn't a designated fire door before you take it out.

RULES

KNOW THE RULES

If this opening is part of a fire escape route in a flat or HMO, Building Regulations Part B may require a fire door. Most bi-fold doors are not fire-rated, so don't fit one in place of a known fire door - check with your landlord, freeholder or building control first if unsure.

BF-02Measure and check the openingMeasure the width and height at top, middle and bottom - openings are rarely perfectly square. Check the reveals are plumb and the head is level. Note any gaps over 10mm, as you'll need packers to true up the fixing points later.

1 pack · Timber packers (various thicknesses)

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BF-03Work out what's behind the reveals and headRun a stud detector or magnet along the head and both side reveals. A hollow sound with regular solid spots roughly 400mm or 600mm apart means a stud wall - a magnet sticking to screw heads in a line tells you it's metal studs, not timber. Drill a small pilot hole in an inconspicuous spot: fine pale dust means timber, grey metal swarf means a metal stud track, solid resistance all the way means brick or block, and a hollow zone that then goes solid means dot-and-dab plasterboard on masonry. Lath and plaster gives a soft, slightly springy feel with a lot of hollow sound between narrow timber laths.

1 each · Stud detector

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BF-04Do your safety checks before you drillCables and pipes can run almost anywhere, including up reveals and across heads near sockets or lights above. Use a detector, but still assume something could be there until you've proved otherwise - detectors miss cables that are deep, in conduit, behind metal-backed board, or hidden by a metal stud frame. Find your stopcock now (usually under the kitchen sink) and check it turns freely. If you have any doubt at all, isolate the relevant circuit at the consumer unit before drilling, and turn off the water at the stopcock before cutting into anything that could carry a pipe.

BF-05Fix the top track to the headIn solid brick or block, drill 6mm holes 40mm deep, insert wall plugs and use 50mm screws. Into a timber stud, drive a wood screw straight into the centre of the stud - never just into the plasterboard skin. Into a metal stud, use self-drilling metal-stud screws or a toggle-type hollow-wall anchor - a plain wall plug or ordinary wood screw will strip straight through 0.5mm steel. Through dot-and-dab plasterboard, use a fixing long enough to pass through the board, the adhesive dabs and into the masonry behind - typically 60-75mm. Into lath and plaster, locate a timber joist or noggin behind the laths and screw into that, or use a toggle fixing rated for the weight, since the laths alone are too fragile to hold a screw. Bi-fold doors get pulled and pushed every time they're used, so a screw into plasterboard alone - stud or not - is never enough on its own; fix into solid timber or masonry wherever you can.

1 pack · Wall plugs and 50mm screws

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1 pack · Self-drilling metal-stud screws

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1 pack · Toggle-type hollow-wall anchors

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1 pack · Long fixings for dot-and-dab (75mm)

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BF-06Fit the side guide channelsHold each channel plumb against the reveal, packing out any gaps found in step BF-02. Fix at roughly 400mm centres using the same wall-type rules as the head track. Check both channels are plumb and parallel before fully tightening any screws.

1 pack · Screws (size per wall type from BF-05)

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BF-07Hang the door panelsLift each panel into place and engage the top pivot pin into the track. Lower the panel so the bottom pivot or guide pin drops into the floor channel. Check the panels swing and slide freely before moving on.

BF-08Fit the floor guidePosition the floor guide centrally under the leading panel and mark the fixing holes. On a timber floor, use wood screws directly. On solid concrete or screed, drill, plug and screw. Check the panel isn't binding on the guide once fixed.

1 pack · Wood screws (25mm)

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1 pack · Wall plugs (for concrete floor)

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BF-09Adjust and test the doorAdjust the top pivot height so the panels hang plumb and clear the floor evenly - check with your spirit level. Adjust roller or pivot tension so the panels don't drag. Open and close the door fully several times, fine-tuning until it runs smoothly.

BF-10Fit handles and trimsFit any handles or knobs supplied with the kit. Fit edge trims or an astragal strip between panels if included, and refit or add architrave to cover the fixing points at the head and reveals.

2 each · Door handles/knobs

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1 set · Architrave

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BF-11Clean up and final checkRemove any protective film from the panels, vacuum dust from the track and floor guide, and wipe everything down. Do a final open-close check and tighten any fixings that have worked loose.

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